1. Field of the Invention
The present invention is generally related to a conjugated compound, and more particularly to conjugated compounds containing a hydroindoloacridine structural element and application thereof.
2. Description of the Prior Art
At present, phosphorescent metal complexes have been used as phosphorescent dopants in an organic light emitting diode. Among these metal complexes used in the light-emitting layer of the organic light emitting diode, cyclometallated iridium complexes have been extensively researched since their electron configurations have strong spin-orbit coupling. Since spin-orbit coupling results in mixing between the singlet and triplet excited states, the lifetime of the triplet state is greatly reduced and thereby the phosphorescence efficiency is promoted. In addition, it is found that the doping method can also enhance the efficiency of the device. Therefore, the method of doping phosphorescent substance in a host material is utilized and thus the research in blue phosphorescent host materials becomes important. In the earlier reports, the majority of the blue phosphorescent host materials are carbazoles. Carbazole derivatives have high triplet-state energy and are suitable as the blue phosphorescent host materials. In view of the above matter, developing a novel organic compound having high heat stability and high triplet-state energy to prolong the usage lifetime of the device and to increase luminance efficiency is still an important task for the industry.